Interest calculator



8- 1949. J. A. BROWN 7 2,477,785

INTEREST CALCULATOR Filed March 4, 1946 2 Sheets-Sheet 1 INVENTOR.

m2 flim ATTORNE Y5 Aug. 2, 1949. BRQWN 2,477,785

INTEREST CALCULATOR Filed March 4, 1946 v 2 Sheets-Sheet 2 INTEREST CALCULATOR.

BLUE

RED

. 24 Q w" 2, B

f (7M7 Fig4 W a W ATTORNEYS Pa'tented Aug. 2, 1949 UNITED STATES PATENT OFFICE.

INTEREST CALCULATOR James A. Brown, Houston, Tex.

Application March 4, 1946, Serial No. 651,801

8 Claims. 1

This invention relates to interest calculators for facilitating computation of interest for various elapsed time periods. More particularly, this invention is directed to interest calculators adapted for use by public utility companies, such as gas companies and electric companies, which require consumer deposits of comparatively small amounts, on which interest is paid at regular intervals, as annually, where the deposits remain more than six months-no interest being paid on deposits made less than six months prior to discontinuing service.

One of the objects of this invention is the provision of an interest calculator which will quickly and accurately indicate the amount of interest due a customer who withdraws his deposit on some date other than the regular periodic interest-payment dates from a company ordinarily paying interest on such deposits only on specified dates, as, for example, on December 31st of each year.

Another object of this invention is the arrangement in juxtaposition in a calculator, of tables separately indicating the interest due on amounts usual for customer deposits for a. The number of months since the last interest payment,

I). The number of days beyond complete months, and, if desired,

0. The number of complete years, with a cooperating slide adjacent each table readily adjustable to various positions corresponding to different elapsed time periods for the deposits.

Other objects and advantages will be apparent from the following description taken in connection with the accompanying drawings showing by way of example preferred embodiments of this invention.

In the drawings:

Fig. 1 is a plan view of an interest calculator constructed in accordance with this invent-ion;

Fig. 2 is a vertical cross-section taken substantially on line 2-2 of Fig. 1;

Fig. 3 is a plan view of a modified form of interest calculator; and,

Fig. 4 is a vertical cross-section taken substantially on line 44 of Fig. 3.

Referring now to the drawings, the numeral l0 designates a base plate provided with a plurality of laterally spaced grooves ii and i2 and plurality of interest tables adjacent each of said grooves. In the groove H is arranged a slide I3 bearing on its face a plurality of indicator divisions in each of which is mark-ed a month of the year. In Fig. 1 the slide is shown bearing l8 indicating five months on table ll.

months, each in its separate division space, and indicating each month of the present year and the last six months of last year. In the groove [2 is arranged a slide l4 bearing on its face a plurality of indicator divisions bearing consecutive numbers corresponding to the days of a month. In Fig. 1 there are 31 such indicator divisions on slide l4.

Cooperating with the slide I4 along one side thereof is an interest chart composed of a pair of duplicate tables Ho and l5b, respectively, arranged end to end. Table l5a has thirty-one indicator divisions and table l5b thirty divisions. The zero or bottom division of table [5a is designated 50 and is aligned with an index I6, herein shown as an arrow. The duplicate interest tables 15a and 15b are colored in contrasting colors, as for example, the upper table [So being colored blue and the lower duplicate table l5b being colored red.

Cooperating with the slide l3 in close juxtaposition along the respective opposite sides thereof, in Fig. 1 is a pair of interest tables I! and I 8 respectively. Table I! is arranged at the left of slide l3 directly above an index I9, herein shown as an arrow, and comprises 12 indicator divisions, each of which is subdivided horizontally into a pair of indicator spaces alternately colored with the same colors as in the duplicate tables l5a and I5b hereinabove described. Similarly the table i8 is composed of 12 indicator divisions, each of which is subdivided horizontally into a pair of indicator spaces alternately colored with the same contrasting colors as tables l5a and l5b. However, table I8 is arranged at the right of slide 13 and its lowest indicating division is spaced a predetermined distance above the lowest indicator division of table I! equal to the space needed for In other words, the lowest indicator division on table [8 is in alignment with the sixth month indicator division on table 11.

In each of tables I! and I8 the lower subdivision of each indicator division is colored with the color borne by the lower interest table I51), and the upper subdivision is colored to accord with that of the upper interest table I5a. Furthermore, the indicia in the upper subdivision space in each indicator division of tables I! and I8 is the same as the indicia in the lower subdivision space in the next higher indicator division.

terest tables la, I51), I! and I8 are shown with only two interest indicating columns, by way of example. These columns, however, show the interest due on the most popular amounts for customer deposits in public utility companies, to-wit: $5.00 and. $10.00 respectively. Beginning at the left in Fig. 1, the first column on table I! is marked with the reference character A and shows the number of months; the neXt column, B, shows the interest due'on a deposit of $5.00 for thevarious monthly time periods shownin column A, and the third column, marked with the reference character C, similarly shows the interest due on customer deposits of $10.00 for various e'lapsed monthly periods. Table I8, arranged at the right of slide l3 (marked at its top with the reference character D) is also composedofthree columns, showing respectively the interest due forvarious elapsed monthly periods on customer "deposits of $5.00 and $10.00 and the particular elapsed diiGDtIilylpe'iiOZiS. ItWill'be noted, however, that thesecominns are 'reverseiy ar'ranged with respect to -tho's'e 'showh in'table'tl the column-E indicating interest amounts due on $10.00 customerfd'eits'be'irig'neXt to the slide 13, the column F b ngint'erest amounts due (in $5.00 customer "deposits being nXt"to'- the- .00 interest column, and column G, showing the number of -ino'nth's, b'eih'g' at the-'eXtrerneright'of table [8.

Tables l5a-and lfibare arranged with a guide "column, marked with the reference character K, indicatinglthe numberf' o fpdd days on' whichin- 't'erestis-to be'paid, a column J showing the intere'stamounts due on customer deposits of- $5.00" f or various elapsed period of'days" up to ohe month, arid acoluinnI, bearing the interest amounts-due tneustemer deposits of$l0.00 foryarious-"numiters of days up to one month. V

The embodiment illustrated in Fig's. "1 and'2 is particularly designed for use by a'cerhpany mekir'i'g "ai-practice of paying interest on customerdeposits on December Blst'tfeachwear, where the amount-deposited *has been left with the'm for *ino r'e than six months. if the deposit is made in *an'yfyear prior to- July lst, interest payment is deo'n De'cember 31st 6r that-year. *"Howv if the depositis'm'ade'in anyyea' after 'qune'iloth, then interest-payment 'is' not paid until- December 3 1st; in the following year. It must be "kept in j'mind thatfio'interest is paid. on any'de'posit made 1 less than six hionths before discontinuing service andfivithdrawingthe deposit.

inbp'erati'on -this interestcalculatoris adapted for use by a companywlio'se policy istopay in- 'te'rest' on December 3 st ofeach year on all acfi'iounts which are six months-older 'older' 'on that dtafte If, when an account -is'closedfno*such p yment-hm fallen due "on the accountjthen "in calculating the int'erestto be paid for the comfplt'e or even-months the reading Will always be I taken from table 18. On the other hand if-such December 31st interest payments have previously ijal lendue onthe account to'be' clos'ed. thentable "l'i'is'used' to figure the interest for the complete even months;

it is believed that theope'ration er my improved 1 interest calculator can best be 'ilustratec'lby delin'eating' its use, tOfWlt.

case A. Wherethe customer-has alresay'rebeiired at least one"December 31st in'terest-payi "menfipr'i'or'to closing the account.

Case B.Where the customer has not received culator for each of these cases will now be given; Case A.Gustorni opened his account with a $10.00 deposit on August 20, 1940; and closed his account September 18, 195; It will be remem= bered that interest from August 20,1940 to De cember 31, 1940 Was paid on December 31, 1941; along with the 1941 interest payment. In addition, the last interest payment, made on Deceni= ber 31, 1944,.paid the interest up until that date. interest due then is onlyffor 'the -lg ht months 'and'18 days of the year1945.

To calculate the amount of this interest slide T4 is moved until the index arrow l6 points to the numeral '18. Slide l4 will remain in this position for any other calculations made on this day for othercustomers, and may be set in the morning-of eachday to be ready for computations of interest of all customers withdrawing deposits thatday. As the interest payment is from December 3 1944, a reading on the scale opposite "31 will be made in column The v'alue i03 is thereshowm an'd 'this represents $0103. Ne'Xt the slide I3 is set-*Sothat the index-"arrow 19 points -to-septembn The'reading on column c f chart 41 is taken opposite *the month from which the interest is to 'b'e cal'culated,to-'wit: Dec'eniber or last year. in this column (I, the 'di'visien in alignment with December of met -year, bears-two subdivisions "contrastingly colorcd. :Ihe figure =i's read whicn-corresponds in olor toithat opp'csite the numeral read in column in table wbgwli'ere the $0.03 indication was obtained. lt happens in" this instance that such table is colored reii' -and accordingly the red poi'tion of 'theindicatdr-di- -visionin' column C should hre be used. The numbentnere indicated is :40 which" is thenadded to tlie I03 indication' obtained from co1umn I to giyethe t0ta1-' -il1'tei'-'estdue of $0543.

Case B.-==For this-xainple wewillassumethat the-customers acccunt was o eneu hpr'iiz, 1e45, with a $10.00 deposit and that customer desires tomosetne accouht on oecember 'v, 1945. Slide Wi is moved so 'that the iridx- 'arrow T6 pointsto tl'iehufiii'aP T Asinterest 'is to be pai' d rom April 2, the reading opposite fl on slidellis taken. lt -will be -seen -that misreadingindicates .01 in the bluecolored table 15a. slide tiis tlie'n set-sotllatt'lie 'index' arrow "I 9 "points'to December of this year. The reading 'for this case will be in "t e column matked -h ofchart i8as"no December "31st intie'st' payrnnt n'a's been made on the account. The reading opposite April-will be taken whih correspencs" n 'color to -that obtained in to-wit blue-color oftable [5a. This "Value is indicated as 40, =aiid the-- two valuesob- "tai'tid' aie added 'to give" the total interest due -'i)f $41. -It" wi-ll be iioted that the indications in columns B and C of table IFcOrrespOnd With those in columns E and F of table luwherevef the two*tables ovrlap. I f 'an-"operator attempts to make interest pm' ment *on'unaccount which is 1 less than-six irionths-oldj the *reading would fall in the blank space below taole -18, reminding the-operator thatno interest was due -on such account.

Referring -now "to the modification "shown in Figs. 3 and 4, it will be obsei'vedthat thebhart I for indi'cating the-number i of days less than a complete month 'is "identical"with 'that shown in the above described 'eiiibodimentand consistsof the ccmtrastingly col6rd 'tab es -l'5a and- [Sb-arranged respctii/ely abcve and bldw"one another with t'he zero iridicati6n alig'ned with tiie 'iiidex arrew 6. rhe' cehtmrchart in is util-ized 'for deter'niining' t-he-interest auetn' complete months less than an entire year, and the chart 2| at the left of Fig. 3 is utilized for determining the interest due on complete years of an elapsed time period. The arrangement of chart 20 differs somewhat from the arrangement illustrated in the first described embodiment in that it comprises upper and lower tables 20a and 2% respectively positioned above and below a central horizontal division line 22 toward which points the index arrow 10. The table comprises twentythree divisions, and each division is subdivided into upper and lower contrastingly colored spaces, corresponding to the colors of the upper and lower tables I51; and l5b in the chart at the right of Fig. 3. The central division is divided by the horizontal division line 22 forming the upper and lower tables 20a and 202). A slide 23 is arranged adjacent chart 20 in a substantially central groove 24, and this slide is divided into 12 indicator divisions labeled consecutively from the top with the months of a year.

Chart 2| also comprises upper and lower tables 2 la and 2 lb respectively, but unlike charts [5 and 20 they are not duplicates of each other. The upper chart 2la comprises 20 indicator divisions bearing interest computations for $5.00 and $10.00 deposits in adjacent columns. The lower table 2 lb comprises only 19 indicator divisions marked to designate interest computations for up to 19 years for $5.00 and $10.00 deposits in adjacent columns. A horizontal division line 25 is arranged between the upper and lower tables Ma and 2H). The reason for the diilerence in number of indicator divisions in charts 2la and 2lb will be apparent from the following examples of the use of this modification.

The modification illustrated in Figs. 3 and 4 is particularly useful for companies that do not pay interest each year, and can be used for determining interest calculations where entire years are involved. Assume that on July 17, 1941, a $10.00 deposit was made in opening an account, and the account is being closed on September 12, 1945. The slide 14 in the right hand groove is moved until the index arrow [6 points to 12 (day on which account is closed). The reading then is taken opposite the numeral 7 (indicating day on which account started) in the interest column for the $10.00 deposit. This amount is $.04 in the lower table i512, which we will say is colored red. The slide 23 in the central groove 24 will next be moved until the index arrow I9 points to the month September (when account is being closed), and the reading will be made in the indicator division opposite the month July (when account was opened). Which contrastingly colored subdivision of such indicator division is to be used is determined from the color of the table (5a or l'5b utilized in computing the interest for the days less than a complete month. In the present example the lower red table I519 was used, so here the red or lower subdivision opposite July on the slide 23 will now be employed. The reading there shows $.05, and will be added to the $.04 previously determined from the days column at the right of Fig. 3. This combined figure of $.09 represents interest from July 17 to September 12, and leaves only complete years for further interest computation. The amounts due for interest on deposits for complete years is readily found in the chart 2! at the left of Fig. 3. In the present example, slide 25 in the left groove 2'1 in the modification shown in Fig. 3 would be moved until the indicator division bearing the year 1945 is aligned with the indicator arrow, substantially as'shown.

The reading would then be taken from table Na in the indicator division opposite 1941 (year in which account started) in the column for $10.00 deposits. This figure is $2.40, and should be added to the $.09 previously determined as interest due for the partial period over and above complete years. The reason for using the upper table 2|a in the present instance is because the indication for the months obtained from the central chart 2!! was above the heavy horizontal line 22. When the interest for the months is determined from the scale above such line 22, the upper chart 2m in the left column is used, and vice versa if the reading for the months in the central column is obtained from the chart 20b below the horizontal line 22.

As previously described the upper table 2la covers a period of 20 years while the lower table 2Ib covers a period of only 19 years. The reason for this difference may be readily understood by considering an example involving nearly complete years. For example, if an account was opened September 11, 1941 and closed on September 11, 1945 interest for exactly four years would be computed. Should the account have been closed out on September 12, 1945, the elapsed period would be four years and one day. In such instance the upper chart 21a would be employed. On the other hand, had the account opened on September 11, 1941 and been closed out on September 10, 1945 the account would have been in existence for three years, eleven months and twenty-nine days and the lower table 21b would be employed, because it would be found that in such instance the lower chart 20b of the central table would have been utilized in computing interest for complete months.

It has been found that my improved interest calculator speeds up the computations of interest under unusual conditions such as hereinabove described to a marked degree. Unskilled oper ators can be taught its use within a very short time, and their computations can rapidly be checked by a supervisor.

While I have illustrated and described what I now regard as practical and efficient embodiments of my improved interest calculator, it is to be understood that the constructions shown are merely illustrative and susceptible of Various changes or modifications within the spirit and scope of my invention.

Having described my invention, I claim:

1. An interest calculator to enable the rapid determination of amounts of interest by the day, for a predetermined principal at a pre-determined rate, comprising a base plate provided with a groove; an interest column having a, number of divisions arranged alongside the groove, the number of divisions being grouped into two fields of thirty divisions each equal to the number of days in a commercial month; a zero division interposed between the two fields and common to both, the divisions of each field containing pro-calculated interest amounts for a predetermined principal at a fixed rate of interest. said interest amounts being duplicated in the corresponding divisions of the respective fields; a single slide shiftable in the groove and common to each of the fields of the interest column, said slide havin a series of thirty-one divisions corresponding with the number of days in the longest months; and an index marker fixed on the base plate in line with said zero division, the slide being adjustable along the groove to position one or another of its divisions in line with n lfie dal V nnuinter stn alculetor narineea: base at eroridedw tna ereo e;- a air f teres tab t d s ayin nt rest-amen rne bye stemmed; t a prede ermin rate; 2; .i eeestc o i qcesfii elh nqli asingj numb rs? on days. in 1 a. month; he intere t.- tables ei g; substantiali dup i at s: i r ea h: ERY n Jenni:

di alongside ne. f; aid eroe es l n ex,- markerinxedeon the l t l t a point h tweenstn wo in res tables. nnda sine de healing. a single. ran e: o umber l enrese g r the days of a month, and shiftable in the g ro ye; to, coact with one ,or. theother. oi the, duplicate interest tables, said slid being; adjustahlel rel ativelyi to the fi-xedlindex; marker-w s able; the;

selection of the correct amount of interestduc 20, senting days of a month, shiitable in, the groove,

on any number of days in a month.

3: An interest calculator, having a base plate, provided with a plurality of laterally-spa ed, grooves, an index marker, and at least ,oneinter; estrtable. beside each groove, and indicia -bearing slidesfmovably mountedin said grooves calibrated according to-selectedtime units and ,respectiyely cooperatin withthe adiac nt ab e nepi s id; interest; tables. comprising a duplicate pair oi contrastingly. colored char s, each a in Iiilfln: u dioator divisions-1andarranged-respgctiyelyaboye andbelomits indexfmarker, the slide, cooper atin swith said duplicate, table bearing 31in; dicator divisions positioned to cooperate with either ori both of said charts, and anothenofsaid to interest. tables;, ari a h. 55; ts iI Q QK Q1? visionssubdiyided intonpper and lower spaces, alternat lyecolored ithtl e celere bgtn rby, sa uplic te ables:

4-;nninterest; alenlatqlxneri-n eelbeses lnia p ovided with th ee lat al ate; er e eei denim rise 122 91.:01 --the h he e ds: fe nn er ovesv. mounted on the base plate; o ld-fimllfilqfia totalfino istsori he b in ide due upon the. ame: nee s l same telie c m let amounts arran d by halt men a. new f r th leak h es 0 he monthsqb inei n 'c Lw fen-the firste alv u ce in both fie ds of the nirdoi-said harts. tere Qnntsd eupQ th S ignations and slidable in; the g 0V6 adjacent he re h rt n e N year designationsand slidalol ad e en e-two ld ,a tt my Been con e utive ea -fie thly interest amounts.

ma forleach chart, each of which markers pies ,a fixefd relation to its appropriate chart,

he groove with which its chart isasso} a,sli de. ,bearing the '31 numerals reprealongside the chart bearing thefinterest' amounts f a month, said interest amountsrunes Yely in the same direction, and

said, chart, "single interest sums being indie U bearing spaced month designations, shiftah ei thejgr oye, alongside tnechart bearing the, interest amounts for, complete months, said lasted-interestamounts being computed for half and the, monthly designations on the sli, lacing ofsuch area as to indicate two semi-5 nionthlysums, the sel ection of the proper sum he g determined by the location of the indi-' cated days" interest amountin the upper or lower.

of; reee'a sulated; nt est amounts basednn a predeter hied surn at'a predetermined rate for succ siye ,daysof-aunonth, the series of interest amounts-on the respective fields being duplie sated.-

a dnroer ssine nt e e ir c i n; markenfixedly related-to the days interest .t; al lnele. sl der ali ne a list n a from; .1f-f: t9 .31 representing the days of. the theislide beingshiftable relatively to the da sinterest chartand to the index marker to in pate interest arnQuntsin either field or-the day. nt restoha t; the mo t s n e rt nlclndinei a i t i: pr s i e y increasing n: ter st) amounts, a u a e se ih y a d A arne pz edetermined sum and rate; an inde mar r fixed related ot e months nteres echart; a-sl de b a n a t f month l ignatior sandbeing'shiftaple relatively to the men interest amount chart, and to its index 1$$ toindicate both thehigher and lower sen; n' entl' ly interest amounts of a selected month,- the locationof the indicated days in Inountiri the iirst-or-second of the, suc- 4 duplicate. fields of the days interest l nt chart determining the election of the he (tr-lower sernir-monthly interest amount t o indicated;v by the second named slide. interest calculator having a base plate pr videdfwith, a, plurality. of. laterally spac'ed es anfi ndex rnarker, at least-one interest e 1 each groove, and indicia-bearing I ountedin; the groo and calibrated. in difieren units or time, said 1 slides respectiyelii an. ad a e t in e est tablet an djiistmentoi said, slides relag tit; yttdg'th'el respective index markers, and by the location'of saidnindication in the upperorl; lower'field of, the 'dayslinterestamount chart, or in'the upper or, lower position of. the selected gsubstanti 1y duplicated, on both fields of d'bj thelsinglenurnerals on the slide; and

interest tables based on predetermined sums at selected rates for time units corresponding to the calibration of their adjacent slides, said interest tables adjacent one slide being arranged in duplicate visually contrasting sections, said sections positioned respectively above and below the index marker, and said tables adjacent another slide having each of its indicator divisions subdivided into visually contrasting upper and lower spaces corresponding with said contrasting sections of said duplicate tables.

8. An interest calculator having a base plate provided with a plurality of laterally-spaced grooves, an index marker, at least one interest table beside each groove, and indicia-bearing slides movably mounted in the grooves and calibrated in difierent units of time, said slides respectively cooperating with adjacent interest tables, said interest tables based on predetermined sums at selected rates for time units corresponding to the calibration of their adjacent slides, said interest table adjacent one slide being arranged in duplicate sections contrastingly col- 10 ored and positioned respectively above and below the index marker, and said table adjacent another slide having each of its indicator divisions sub-divided into upper and lower spaces, respectively colored to correspond with contrasting colors of said duplicate tables.

JAMES A. BROWN.

REFERENCES CITED The following referenloes are of record in the file of this patent:

UNITED STATES PATENTS 

